| 摘要 |
PROBLEM TO BE SOLVED: To realize a control so as to protect an electric motor from high temperature when a large load is applied to the electric motor by setting the PWM control frequency to be smaller than the prescribed value when the load not less than the prescribed value of the electric motor is detected. SOLUTION: When a microcomputer 12 detects the load of an electric motor M not less than the prescribed value, i.e., when the microcomputer detects that the current flowing in the electric motor M is not less than the prescribed value, the PWM control frequency is set to be smaller than the specified value. An accelerator volume 14 to output the indicated speed signal and a speed detection circuit 20 to detect the actual traveling speed are connected to the microcomputer 12, and the microcomputer 12 detects that the difference between the indicated traveling speed and the actual value becomes not less than the prescribed value. The PWM control frequency when the current detection circuit 16 detects the load not less than the prescribed value is the frequency at which the current flowing in the electric motor M is close to the value when traveling on a slope of maximum climbing angle. The temperature rise of the electric motor M can be suppressed. |
